1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a method of producing the electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus.
2. Description of the Related Art
In recent years, for the purpose of extending the life of an electrophotographic photosensitive member, improving image quality, and increasing the processing speed of an electrophotographic apparatus, it has been desired to improve the mechanical durability (abrasion resistance) of an organic electrophotographic photosensitive member containing an organic photoconductive substance (charge generating substance) (hereinafter referred to as an “electrophotographic photosensitive member”). In order to improve the mechanical durability, in accordance with one technique, a surface layer of an electrophotographic photosensitive member contains a polymer produced by the polymerization of a compound having a polymerizable functional group.
Japanese Patent Laid-Open No. 2000-066425 discloses a technique for providing a surface layer with a polymer produced by the polymerization of a charge transporting substance having two or more chain-polymerizable functional groups to improve the abrasion resistance and the electric potential stability of an electrophotographic photosensitive member. Japanese Patent Laid-Open No. 2010-156835 discloses a technique for providing a surface layer with a charge transporting substance having two or more methacryloyl groups per molecule and a polymer of a composition containing no polymerization initiator to improve the mechanical durability (abrasion resistance) and the electric potential stability of an electrophotographic photosensitive member.
However, with an improvement in the mechanical durability (abrasion resistance) of an electrophotographic photosensitive member by these techniques, image deletion is more likely to occur.
Image deletion is a phenomenon in which a blurred electrostatic latent image results in a blurred output image. It is believed that the reason for image deletion is that discharge products resulting from charging remaining on the surface of an electrophotographic photosensitive member decrease the surface resistance of the electrophotographic photosensitive member.
The present inventors found that the technique described in Japanese Patent Laid-Open No. 2010-156835 tends to cause distortion of a charge transporting substance, resulting in insufficient electric potential stability and prevention of image deletion in repeated use.
The present inventors also found that, among the chain-polymerizable charge transporting substances described in Japanese Patent Laid-Open No. 2000-066425, a charge transporting substance having a methacryloyloxy group has a higher image deletion preventing effect than a charge transporting substance having an acryloyloxy group but has more room for improvement in terms of image deletion and electric potential stability.
Japanese Patent Laid-Open No. 2007-279678 discloses a technique for preventing image deletion by providing a surface layer containing a curable resin of an electrophotographic photosensitive member with a particular amine compound. However, the image deletion preventing effect is insufficient, and the electric potential stability of the electrophotographic photosensitive member tends to deteriorate.